Cameroon opposition leader Issa Tchiroma Bakary has unilaterally declared victory in the country’s presidential election.

Tchiroma made the statement in a nearly five-minute speech posted to social media early on Tuesday. Although official channels have not declared results, he urged long-term incumbent, 92-year-old President Paul Biya, to call him to concede.

“The people have chosen, and this choice must be respected,” Tchiroma demanded in the video.

However, the government warned earlier this week that only results announced by the Constitutional Council can be considered official. The body has almost two weeks to make the announcement.

A former government spokesman and ally of Biya for 20 years, Tchiroma was considered the top contender to unseat Biya in Sunday’s elections.

After he resigned from the government in June, his campaign drew large crowds and key endorsements from a coalition of opposition parties and civic groups.

But Biya – in power for 43 years and the world’s oldest serving head of state – has been widely expected to secure another seven-year term in office, given his tight grip on state machinery and the fragmented nature of the opposition.

Cameroon’s government has not responded officially to Tchiroma’s declaration.

However, Minister of Territorial Administration Paul Atanga Nji warned recently that only the Constitutional Council has the authority to announce the winner, and that any unilateral publication of results would be considered “high treason”.

Cameroon’s electoral law allows results to be published and posted at individual polling stations, but final tallies must be validated by the Constitutional Council, which has until October 26 to announce the outcome, the Reuters news agency reported.

In the video, filmed in his northern hometown of Garoua in front of the national flag, Tchiroma urged Biya to “honour the truth of the ballot box”, and to concede and offer congratulations.

Doing so, he said, would be a mark of Cameroon’s political maturity and the strength of its democracy.

The election results, he said, represent “a clear sanction” of Biya’s administration and marked “the beginning of a new era”.

Tchiroma also thanked rival candidates “who have already congratulated me and recognised the will of the people”.

He called on government institutions and the military to recognise his victory and “stay on the side of the republic”.

“Do not let anyone divert you from your mission to protect the people,” he said.